The U.S. Postal Service has defined “curbside mailboxes” as any design for a mailbox made to be served by a carrier from a vehicle on any city, rural or highway route.
A common design for a curbside mailbox is shown in FIG. 1A. The mailbox 100 comprises a container 101 mounted on a post 102. The container 101 is defined by a top member 104 formed sheet of metal which provides two parallel, vertically-oriented side walls 106, 108 with a dome-shaped roof portion 110 in between the side walls. The bottom edges of the side walls 106, 108 are riveted to a bottom panel (not shown) which provides the floor of the box 100. The side walls 106, 108 and roof portion 110 leave open ends at the front and rear of the container 101. The front end of the box (the end nearest the road) is closable by virtue of a door 112 attached to the bottom panel by a hinge. The rear end of the container 101 is closed by an end panel (not shown) which may be soldered, riveted or otherwise fixed to the top member 104 and the bottom panel. A flag 114 on wall 108 is movable by hand from a horizontal position to a vertical position to enable communication between the mail customer and the mail carrier through movement of the flag from one position to the other.
Another, less common prior art curbside mailbox 150 is shown in FIG. 1B. Mailbox 150 is configured as a right triangular prism having a first side 152, a second side 154 and a hypotenuse side 156. As shown, the first side extends horizontally from the intersection with the second side 154 to serve as the bottom panel. The second side 154 extends vertically upward from the first side at a relative angle of about 90 degrees. The hypotenuse side 156 which faces oncoming traffic, slants downward from the top of the second side 154 to meet the distal edge of the first side 152. The mailbox 150 has two ends, including a front end 158 which includes a door 160 for inserting or removing delivered items. There is a second door 162 in the second side 154.